.\" pppoe-discovery.8 written by
.\" Ben Hutchings <ben@decadentplace.org.uk>, based on pppoe.8.
.\" Licenced under the GPL version 2 or later.
.TH PPPOE-DISCOVERY 8 "12 January 2019"
.SH NAME
pppoe\-discovery \- perform PPPoE discovery
.SH SYNOPSIS
.B pppoe\-discovery
[
.I options
]
.br
.BR pppoe\-discovery " { " \-V " | " \-h " }"
.SH DESCRIPTION
.LP
\fBpppoe\-discovery\fR performs the same discovery process as
\fBpppoe\fR, but does not initiate a session.
It sends a PADI packet and then prints the names of access
concentrators in each PADO packet it receives.
.SH OPTIONS
.TP
.BI \-I " interface"
.RS
The \fB\-I\fR option specifies the Ethernet interface to use.
Under Linux, it is typically eth0 or eth1.
The interface should be \(lqup\(rq before you start
\fBpppoe\-discovery\fR, but should \fInot\fR be configured to have an
IP address.
The default interface is eth0.
.RE
.TP
.BI \-D " file_name"
.RS
The \fB\-D\fR option causes every packet to be dumped to the specified
\fIfile_name\fR.
This is intended for debugging only.
.RE
.TP
.B \-U
.RS
Causes \fBpppoe\-discovery\fR to use the Host-Uniq tag in its discovery
packets. The value of the tag is derived from the process's PID number.
This lets you run multiple instances of \fBpppoe\-discovery\fR and/or
\fBpppd\fR without having their discovery packets interfere with one
another.
You must supply this option to \fIall\fR instances that you intend to
run simultaneously.
This option is mutually exclusive with \fB\-W\fR.
.RE
.TP
.BI \-W " value"
.RS
Causes \fBpppoe\-discovery\fR to use the Host-Uniq tag in its discovery
packets. The value of the tag is taken from the option argument,
encoded as a string of hexadecimal digits.
This lets you run multiple instances of \fBpppoe\-discovery\fR and/or
\fBpppd\fR without having their discovery packets interfere with one
another.
You must supply this option to \fIall\fR instances that you intend to
run simultaneously.
This option is mutually exclusive with \fB\-U\fR.
.RE
.TP
.BI \-S " service_name"
.RS
Specifies the desired service name.
\fBpppoe\-discovery\fR will only accept access concentrators which can
provide the specified service.
In most cases, you should \fInot\fR specify this option.
Use it only if you know that there are multiple access concentrators
or know that you need a specific service name.
.RE
.TP
.BI \-C " ac_name"
.RS
Specifies the desired access concentrator name.
\fBpppoe\-discovery\fR will only accept the specified access
concentrator.
In most cases, you should \fInot\fR specify this option.
Use it only if you know that there are multiple access concentrators.
If both the \fB\-S\fR and \fB\-C\fR options are specified, they must
\fIboth\fR match.
.RE
.TP
.B \-Q
.RS
Causes \fBpppoe\-discovery\fR to avoid printing discovered access
concentrator names.
This can be useful in scripts, which can use the exit code of the
program to determine whether any matching access concentrators were
discovered.
.RE
.TP
.BI \-t " timeout"
.RS
Changes the discovery timeout for PADI requests, in seconds.
The default value is 5 seconds.
.RE
.TP
.BI \-a " attempts"
.RS
Changes the number of PADI discovery attempts made.
By default, 3 attempts are made to discover access concentrators before
giving up.
.RE
.TP
.BR \-V " | " \-h
.RS
Either of these options causes \fBpppoe\-discovery\fR to print its
version number and usage information, then exit.
.RE
.SH AUTHORS
\fBpppoe\-discovery\fR was written by Marco d'Itri <md@linux.it>,
based on \fBpppoe\fR by David F. Skoll <dfs@roaringpenguin.com>.
.SH SEE ALSO
pppoe(8), pppoe-sniff(8)
